The present invention relates to cylinder locks of the type comprising a lock body or stator, a cylinder or rotor, rotatably mounted within the body and having a passage for introduction of a key, and a plurality of locking tumblers mounted within the cylinder and having their axes arranged radially, said tumblers being provided for engagement by a key having a predetermined profile in order to be arranged in a condition in which they enable the free rotation of the cylinder within the lock body, wherein each of said locking tumblers is mounted within said cylinder with the possibility to rotate around its axis, said lock further comprising:
means provided on the key and on said tumblers cooperating with each other to cause rotation of each tumbler around its axis, towards a predetermined operative position, upon introduction of the key into the cylinder, and a locking member carried by the cylinder and biased by spring means towards an extracted position in which it engages a cooperating seat within the body, said locking member being free to be withdrawn to a position of disengagement from said seat when the tumblers are rotated to said operative position upon introduction of the key.
Cylinder locks of the above-indicated type are disclosed for example in WO-A-9627724 and FR-A-2736084. In these known locks, each of the above-mentioned rotating tumblers is also slidable axially within a respective bore in the cylinder and is biassed towards the keyway by a respective spring arranged in the bore. The engaging key has a flat surface with a number of spaced apart depressions into which the tumbler tips engage under the action of the biassing springs once the key is fully inserted into the keyway. This arrangement is relatively complicated and costly. Moreover, the provision of the springs renders the device not fully reliable, since the springs may become weaker or be damaged as a result of ambient temperature variations.
The object of the present invention is that of providing a lock of the above indicated type which ensures a high degree of safety and is adapted to provide an extremely high number of different key configurations. A further object of the invention is that of reaching the above indicated result with a lock having a structure which is relatively simple, of low cost and reliable in operation.
In view of achieving the above indicated objects, the lock according to the invention is characterised in that each of said locking tumblers (16) is mounted within said cylinder (10) at a fixed position along the tumbler axis, and in that said means for causing rotation of said tumblers (16) comprises at least one front finger (23) projecting from each locking tumbler (16) and offset relative to the tumbler axis, and at least one shaped continuous slot (23) formed on at least one face (6) of the key (3) and able to receive the offset fingers (23) of the tumblers (16).
In one embodiment, the above mentioned locking rotatable tumblers, are provided in two aligned series on two opposite sides of the passage for introduction of the key. In an alternative embodiment, the lock comprises, in addition to the above mentioned series of rotatable tumblers, a further series of locking tumblers which are radially slidably mounted within the cylinder and are provided to be engaged by the key in order to be arranged in a position in which they enable the free rotation of the cylinder within the body, said rotatable tumblers and said slidable tumblers being arranged in two aligned series on two opposite sides of the passage for introduction of key, said key having a plurality of cavities, adapted to cause actuation of the slidable locking tumblers, on one of its faces, said shaped slot being formed on an opposite face of the key. Preferably, the key has, on its face bearing said cavities, at a position arranged side by side to said cavities, also said means adapted to cause actuation of the rotatable locking tumblers, whereas on the opposite face, at a position arranged side by side to said means for actuating the rotatable tumblers, there is provided a series of cavities adapted to cause actuation of the slidable locking tumblers, so that the key may be used at any one of two positions rotated by 180xc2x0 relatively to each other.
According to a further preferred feature, the key has an axial slot at its end, within which there is arranged a ring mounted with clearance over a transverse pin and adapted to cooperate with an abutment pin which is secured within the cylinder and projects into the passage for the key, so as to push a further locking tumbler carried by the cylinder towards a cylinder freeing position.
Furthermore, the lock according to the invention is preferably characterised in that each rotatable tumbler is constituted by two axially superimposed portions having facing ends having surfaces for there mutual engagement in rotation, so that said portions may be positioned at different relative angular positions, spring means being interposed between said portions for tending to move them axially away from each other, said lock being provided with a first special auxiliary key adapted to be introduced into the passage in the cylinder and able to be withdrawn at a predetermined rotated position of the cylinder, which is intermediate between the opening and closing positions of the lock, at which intermediate position the radially outer portions of the rotatable tumblers are free to engage cooperating cavities in the stator, so that they move apart from the respective radially inner portions of the rotatable tumblers under the action of said spring means, said lock being further provided with one auxiliary change key adapted to be introduced into the cylinder passage when the cylinder is at said intermediate position in order to rotate the cylinder back to the start position, causing again the mutual engagement of the two portions forming each rotatable tumbler, said change key being provided with means for driving rotation of the rotatable tumblers which are different from those provided on the original key of the lock, so that when the two portions constituting each rotatable tumbler return into engagement with each other they assume a different relative angular position, so that the lock is programmed for a key different from the above mentioned original key.